2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors Thyristors A Thyristor is any semiconductor switch with a bi-stable action depending on p-n-p-n regenerative feedback. Thyristors are normally two- or three-terminal devices for either unidirectional or bi-directional circuit configurations. Thyristors can have many forms, but they have certain commonalities. All Thyristors are solid state switches that are normally open circuits (very high impedance), capable of withstanding rated blocking/off-state voltage until triggered to on state. When triggered to on state, Thyristors become a low-impedance current path until principle current either stops or drops below a minimum holding level. After a Thyristor is triggered to on-state condition, the trigger current can be removed without turning off the device. Thyristors are used to control the flow of electrical currents in applications including: control, alarm activation, fan speed) speed, stapling event, battery charging) ignition, electronic displays, area lighting, sports equipment, physical fitness) Sensitive Triacs Littelfuse's sensitive gate Triacs are AC bidirectional silicon switches that provide guaranteed gate trigger current levels in Quadrants I, II, III, and IV. Interfacing to microprocessors or other equipment with single polarity gate triggering is made possible with sensitive gate Triacs. Gate triggering currents of 3 mA, 5 mA, 10 mA, or 20 mA may be specified. Sensitive gate Triacs are capable of controlling AC load currents from 0.8 A to 8 A rms and can withstand operating voltages from 400 V to 600 V. Standard Triacs Littelfuse's products are bidirectional AC switches, capable of controlling loads from 0.8 A to 35 A rms with 10 mA, 25 mA, and 50 mA I GT in operating Quadrants I, II and III. Triacs are useful in full-wave AC applications to control AC power either through full-cycle switching or phase control of current to the load element. These Triacs are rated to with selected products capable of 1000 V operation. Typical applications include motor speed controls, heater controls, and incandescent light controls. Quadrac Quadrac devices, originally developed by Littelfuse, are Triacs and Alternistor Triacs with a DIAC trigger mounted inside the same package. These devices save the user the expense and assembly time of buying a discrete DIAC and assembling in conjunction with a gated Triac. The Quadrac is offered in capacities from 4 A to 15 A rms and voltages from 400 V to 600 V. Alternistor Triacs The Alternistor Triac is specifically designed for applications required to switch highly inductive loads. The design of this special bidirectional chip effectively offers the same performance as two Thyristors (SCRs) wired inverse parallel (back-to-back). This new chip construction provides the equivalent of two electrically-separate SCR structures, providing enhanced dv/dt characteristics while retaining the advantages of a single-chip device. Littelfuse manufactures 6 A to 40 A Alternistor Triac with blocking voltage rating from 400 V to 1000 V. Alternistor Triacs are offered in TO-220, TO-251, TO-252, TO-218, and TO-218X packages with isolated and non-isolated versions. Sensitive SCRs Littelfuse's sensitive gate SCRs are unidirectional Silicon- Controlled Rectifiers representing the best in design, performance, and packaging techniques for low- and medium-current applications. Anode currents of 0.8 A to 10 A rms can be controlled by sensitive gate SCRs with gate drive currents ranging from 5 A to 500 A. Sensitive gate SCRs are ideally suited for interfacing to integrated circuits or in applications where high current load requirements and limited gate drive motor controls, and DC latching for alarms in smoke detectors. Sensitive gate SCRs are available in voltage ratings to 600 V. SCRs Littelfuse's SCR products are half-wave, Silicon-Controlled Rectifiers that represent the state of the art in design and performance. Load current capabilities range from 1 A to 70 A rms, and voltages from 400 V to 1000 V may be specified to meet a variety of application needs. Thyristor Product Descriptions